Protein kinase is an enzyme that can modify the functioning of other proteins by changing enzyme activity, cellular location or protein association. Kinases are known to regulate cellular pathways, especially those involved in signal transduction (i.e., the transmission of signals within the cell).
Hundreds of protein kinases have been identified in the human genome. Protein kinase cell signalling has been implicated in numerous human diseases, including cancer, cardiovascular disease, diabetes, inflammation, arthritis, and Alzheimer's disease. See e.g., Tortora et al., Clin. Cancer Research, Vol. 8, 303-304, 2002; Inagaki et al., Circulation, 111: 44-50, 2005; Koya et al., Diabetes, Vol. 47, 1998; Choi et al., J Cell Science, 119 (7), 1329-1340. 2006.
Compounds that inhibit one or more protein kinases have been investigated for the treatment of various disorders. For example, the inhibition of protein kinase S6K1 has been implicated in diabetes, insulin sensitivity, insulin resistance, obesity, angiogenesis and cancer. See, e.g., Um, et al., Nature, 431, 485, 2004; International Publication No. WO 2005/019829. Consequently, there is continued interest in the development of compounds that act as protein kinase inhibitors.